1. Technical Field
The present invention relates to a detection device, a detection system and a detection method of a radio wave transmitting/receiving body, and particularly to a detection device, a detection system, and a detection method that detect existence of a radio wave transmitting/receiving body in order to prevent a situation where locking is performed, leaving the radio wave transmitting/receiving body in a specific space, so-called containment.
2. Related Art
Recently, an automatic locking function has often been employed to increase assurance and convenience of locking in a vehicle, a building, a locker or the like. Particularly, as represented by a trunk of the vehicle, a mechanism that automatically performs locking at the same time as closing of a door or the like has often been employed. On the other hand, when a key necessary for unlocking is left indoors, a spare key, a specialist for unlocking or the like is needed, and thus, the containment of the key is a consideration on the reverse side of the assurance and convenience of locking.
In recent years, as represented by a keyless entry system of a vehicle, a technique has been known in which transmission and reception of a radio wave are performed between a locking/unlocking control device provided in an object to be locked or unlocked, and a circuit device provided in a key to perform the locking or unlocking of the object. In many of the above-described systems, against the above-described key containment, a signal is transmitted to the key from the locking/unlocking control device to request a return signal from the key and thereby search the key. When it is detected by the search of the key that the key is left inside a space of the object, processing of not performing the locking of the object or the like is often performed. At this time, a situation where the key is not detected although the key is left needs to be prevented. At the same time, a situation where the key is detected in the wrong although the key is not left also needs to be prevented. That is, in order to prevent undetection and false detection, an increase in accuracy of the detection of the key is required.
For example, there are Japanese Unexamined Patent Publication Nos. 2006-77408 and 2006-233533 and the like as the related art that have proposed the containment of the key (portable machine) inside the vehicle or the increase in detection accuracy.
In Japanese Unexamined Patent Publication No. 2006-77408, there is disclosed a locking/unlocking control device for a trunk including a portable machine that records an ID code, which is authentication information specific to a vehicle, an in-trunk transmitter that transmits an in-trunk radio wave to inquire about whether or not the portable machine exists inside a trunk, based on the ID code, a trunk controller that senses/identifies whether the trunk is in an locked state or in an unlocked state, and a smart controller that controls the locking/unlocking of the trunk. The smart controller executes vehicle interior-side processing of checking a history of whether or not the portable machine exists in a vehicle interior at the time of trunk unlocking in accordance with the change from the unlocked state to the locked state of the trunk, and in-trunk search processing. There is disclosed execution of electric processing at the time of containment such as sounding an alarm to inform a user of the containment on condition that it is determined by the vehicle interior-side processing that the portable machine is absent in the vehicle interior, and it is detected by the in-trunk search processing that the portable machine is contained in the trunk.
The technique disclosed in Japanese Unexamined Patent Publication No. 2006-233533 is for a control device to exactly determine whether a portable machine including a radio terminal to which an identification code specific to a vehicle is assigned exists inside or outside the vehicle. In Japanese Unexamined Patent Publication No. 2006-233533, there is a remote operation device for vehicle in which in order to limit a communicable range of the portable machine and a vehicle exterior antenna, which is transmission means, a legitimate identification request radio signal is transmitted from the vehicle exterior antenna as the transmission means outside the vehicle, and at the same time, a disturbing wave to cancel the authentification request radio signal is transmitted from a vehicle interior antenna, which is transmission means inside the vehicle. Transmitting the disturbing wave allows the authentication request radio signal inside the vehicle to be cancelled, so that authentication communication inside the vehicle is not established, but only authentication communication outside the vehicle is established.